Discovery is a wonderful experience, and the great thing about it is that little discoveries can be as wonderful as big ones. This is related to the fractal nature of wonder. If you know a lot about something, the fractal dimensionality of it increases, giving you more, if smaller, blank spaces in which to make discoveries. This discovery happened today, in the studio, rather than three years ago in the field, although that is a significant part of the story as well. So let's set the stage first, and then share the discovery.
I am a very serious student of the vocalizations of Empidonax flycatchers. You might say I am a little obsessed with them. They are everywhere in wooded North America, and so almost everywhere I go, at least in the warm season, I have an Empidonax recording opportunity nearby. I frequently take the bait, especially when it is a species or form I have little experience with. Such a bird is the Southwestern Willow Flycatcher, merely a subspecies (Empidonax traillii extimus) of the widespread Willow Flycatcher, but a vocally identifiable one, as well as an endangered subspecies with a unique habitat for the genus. Its range runs from southern California to the Verde River in Arizona to just south of Albuquerque, south thence to the U.S.-Mexican border, and that is it. A large area, but the bird occurs only in riparian thickets, which, on account of the natural aridity of the area, are rare. Owing to human activity, they have been dwindling in extent for a century and a half. Hence the endangerment of this extreme habitat specialist. I go out of my way to visit known habitat of this form whenever I'm nearby. Such a side trip took me to Roosevelt Lake, Arizona, as I was travelling from Phoenix to Cottonwood Gulch, New Mexico, in late June
Roosevelt Lake is a stronghold of the SWWF, which is ironic, because it too is the result of human activity, a blue tumor, you might say, on what was once the living green of the Salt River Gallery Forest. So, now we have a place that harbors American White Pelicans and nesting grebes and a great many bullfrogs. I took a look at the water birds in the middle of the afternoon on the 29th, found a motel in nearby Punkin Center, and waited in the coolness of my room for the sun to go behind a mountain. It was 105 F. I recorded some bullfrogs that night, but heard no SWWF. Nonetheless, I was out well before dawn the next morning just in case. I recorded whatever I heard for 45 minutes, then hurried along to Gisela for another try, then on the New Mexico. I had too much to do to review my recordings, until now.
Some days I know what I'm going to post well in advance, some days I have several alternatives in mind, some days I have to search. Today I was going to post a Flammulated Owl, which would have been very interesting, but the recording was not quite good enough, so I searched. I knew I had all this unchecked material from Roosevelt Lake, so I finally went through it. I was thinking I might have a good recording of a Yellow-breasted Chat that I could post. I routinely noted a Western Kingbird as I went through the material. Certainly not the dawnsong, just a daytime call. Then I found the dawnsong of a Brown-crested Flycatcher, and I was reminded that the recordings were made well before dawn. Time to check the invaluable Pieplow Field Guide to Bird Sounds of Western North America. Hmm, nothing like that sound on the Western Kingbird page. Oh, maybe Vermilion Flycatcher, although not its dawnsong. No again. Oh dear, of course it sounds like a Tropical Kingbird. Too far north, I thought. I will have to send the recordings to a local expert before posting on eBird. But first, just check the range of the Tropical Kingbird on eBird. I know it ranges up the Pacific Coast from its Mexican breeding areas in fall; I first saw it in Monterey in 1969, a beautiful sight, this brightly yellow-bellied kingbird on a wire by Crespi Pond. But, I thought it was restricted to southernmost Arizona in the breeding season. No, I learn, it ranges farther north, and has been reported right here at the Orange Peel in 2017, 2018, and 2020. So here it is, a Tropical Kingbird. The first few seconds of the recording are pretty good, after that it gets noisy. I filtered out the basso profundo bullfrogs, who have no more business in Arizona than Roosevelt Lake. But, we live with what we've got. Roosevelt Lake's flora and fauna are a wonder in their own right. Just ask the Tropical Kingbird.